Strand casting systems for the discontinuous or continuous production of billets, slabs or the like are known from the prior art.
Rotatably mounted guide rollers are used in the known strand casting systems to guide and cool the metal strand after it leaves the mould. These guide rollers are cooled by water on the inside or on the outside. In order to guarantee the supporting function the axial distances between these rollers must be set precisely depending on the shrinkage behaviour of the casting strand, and this is very time-consuming and can lead to losses of quality and production if these distances are not set sufficiently.
Generic guide rollers of a roller assembly for a strand casting system is known from JP 63072457-A. This roller assembly comprises a plurality of guide rollers which are respectively arranged an axial distance apart from one another along the strand produced by the strand casting system. In the roller assembly of JP-A-63072457 three rows of different guide rollers are provided, a first row of guide rollers being disposed adjacent to the mould exit and comprising a number of rollers with a first diameter arranged a distance apart from one another in the longitudinal direction of the strand that is produced. Adjoining this in the strand direction is a second row of guide rollers which comprises a plurality of guide rollers that have a smaller diameter than the guide rollers of the first row. This second row of guide rollers serves to divert the strand that is produced. Adjoining the second row is a third row of guide rollers which has a plurality of guide rollers that have a larger diameter in comparison to the second row.
As the operating duration of a strand casting system increases, the cross section of the strand becomes greater due to wear of the mould. This gives rise to the problem that the guide rollers, that are arranged in a fixed manner relative to the mould, do not apply the same pressing force to the surface of the strand that is produced over the whole period of use. This may lead to reduced quality of the strand profile that is produced and/or to increased breakout frequency. Moreover, the rollers have to be re-adjusted due to wear from the strand, and this is also labour-intensive and time-consuming.